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Exploring Electromagnets

In this activity, students learn about the relationship between electricity and magnetism by creating and experimenting with their very own electromagnet.

After making the magnet, they can explore how it works by making modifications to the number of batteries, the length of wire and number of loops, and the type of core used.

Electricity and magnetism are linked phenomena.

Moving electrons always create a magnetic field. Electrons moving along a wire make a magnetic field that goes in circles around the wire. When you bend the wire into a coil, the magnetic fields around each loop of the coil add up to make a long , thin magnet with north at one end and south at the other. The more loops the coil has, the stronger the magnetic field, while the current is flowing.

A magnet made from just a coil of wire isn't very strong. But when you coil the wire around an iron nail, the magnetic domains inside the nail line up and make a strong, temporary magnet. If you disconnect the wire, the magnetic field disappears and the nail is no longer a magnet.

If you leave the wire connected long enough, the nail's magnetic domains will realign enough to make it a permanent magnet. But be careful! The current flowing through the wire makes the wire hot and drains the battery quickly.

Objectives

  • Explain the relationship between electricity and magnetism.

Materials

  • Per Demo or Student:
    large iron nail (about 8 cm)
    1 metre of insulated copper wire
    1 fresh D size battery
    paper clips or other small magnetic objects
    tape

Key Questions

  • Is the nail itself a magnet? Does it matter if it is connected to the battery?
  • What happens when a wire is coiled around the nail and connected to a battery?
  • What happens when you disconnect the wire?
  • Why do the wires become hot when they’re connected to the battery?

What To Do

  1. Start about 20 cm from one end of your piece of wire. Wrap it neatly around and around the nail, working your way along the nail. Try not to overlap the coils. Leave another 20 cm of wire free at the end.
  2. Remove about 2 cm of the insulation (plastic coating) from each end of the wire. Attach one wire end to one end of a battery and the other wire end to the other end of the battery. Use tape to connect the wires to the battery, but be careful! The wires can get quite hot!
  3. Put the point of the nail near a few paper clips and see if it can pick them up!

Caution: The wires will get very hot, so never leave the magnet on for more than 30 seconds at a time. Leaving the magnet on for too long could melt the insulation, causing a burn or fire hazard.  Always conduct this activity with adult supervision. Give the magnet plenty of time to cool down between tests. 

Extensions

  • Does changing the number of times you wrap the wire around the nail affect the strength of your electromagnet so that it picks up more paperclips?
  • Can you think of 3 ways to make the electromagnet stronger? (Try altering the number of batteries, the amount of wire, and the type of core you use.)